1. Field of the Invention
This invention relates to a built-in supply voltage dropping circuit, and more particularly the same permitting reduced consumption current.
2. Description of the Prior Art
In recent years, for the purpose of curtailing consumption power, a power supply, which supplies voltages which are dropped by a built-in supply voltage dropping circuit, has been used for semiconductor devices. A semiconductor memory device is provided, for example, with a built-in supply voltage dropping circuit for dropping the supply voltage to the sense amplifier drive circuit.
This built-in supply voltage dropping circuit operates under the control of several activating signals. In detail, these activating signals control turn-on and -off of transistors constituting current-limiting means. Turn ON the current limiter transistors, and the built-in supply voltage dropping circuit is activated to generate a dropped voltage.
A built-in supply voltage dropping circuits in a prior art are required to be designed for good response characteristics to set the current flows through the current limiter transistors to large values. In other words, for rapid generation of a desired voltage from the built-in supply voltage dropping circuit, it is necessary to increase drive current flow in the built-in supply voltage dropping circuit by causing a large current to flow through the current limiter transistors, with the resulting higher speed operation of the circuit.
The built-in supply voltage dropping circuit as described above, however has problem, i.e., large power consumption of the whole device due to a large current always flowing through the current limiter transistors.